I would really like to get some lactic twang up in this at kegging time.

I'm thinking of making a small 1gallon batch of %100 lacto fermented wort with an OG of about 1.025 or so.

My two biggest concerns are these:

1- The amount of sour "starter" needed to significantly lower the pH into twang country, ( 3.8 or lower, but I'm just guessing here), would be significant enough to seriously dilute the base beer and drop the already low ABV to a level I wont be happy with.

2- depending on how much would be needed from the sour side of the blend to sour the base beer, the low IBU level of the sour portion would negatively affect the IBU's of the base beer and throw things out of balance.